The need for both voice telephony services as well as data services is common. Traditionally, this may only be achieved through the use of separate services. For example, dedicated voice telephony services and dedicated data services are provided over separate and distinct networks. This is a significant disadvantage because of the high expense of maintaining and paying for such separate and distinct services, not to mention the inconvenience and inefficiency introduced because voice and data services are not integrated.
Packet-switched telecommunications networks may be based on any of a variety of technologies and protocols such as, for example, Asynchronous Transfer Mode (“ATM”), MultiProtocol Label Switching (“MPLS”), Internet Protocol (“IP”), Frame Relay (“FR”), and X.25. Packet-switched telecommunications networks have data packets, cells, frames or blocks (hereinafter “packets” or “cells”) that are either of fixed length or variable length. Although originally designed to transmit data, as opposed to voice or voice encoded data, packet-switched telecommunications networks may be used for voice communications. Some of the packet-switched technologies that may be used for voice communications include, without limitation, Voice Telephony over ATM (“VToA”), Voice over Frame-Relay (“VoFR”), Voice over Digital Subscriber Line (“VoDSL”), and Voice over IP (“VoIP”).
Focusing on VToA when compared to voice communications or voice telephony provided over traditional circuit-dedicated or circuit-switching telecommunications networks, the use of VToA, unfortunately, presents significant problems and disadvantages, especially in view of the fact that the needs of both data communications and voice communications must be met over the same network. For example, VToA does not provide advanced telephony services and features that are commonly found in traditional circuit-dedicated telecommunications networks. Similarly, advanced signaling, also commonly found in traditional circuit-dedicated telecommunications networks, is not available for VToA in the same manner that circuit-dedicated or circuit-switching telecommunications networks.
To setup and establish a Switched Virtual Circuit (“SVC”) to support VToA between a calling party and a called party, various signaling or ATM messages are used within the ATM network. This may be achieved using ATM setup and connect messages. Once ATM signaling has established an SVC, a data connection is defined and data, such as voice encoded data, may be communicated. Voice encoded data may continue to be communicated until one end of the SVC issues a release message (or any similar message that causes a disconnection). At such time, the SVC is released and voice communications ceases. Examples of traditional ATM signaling used to setup and release point-to-point and point-to-multipoint SVCs for telephony applications is illustrated in the book entitled Hands-On ATM by David E. McDysan and Darren L. Spohn, which is incorporated herein for all purposes.
The administration and maintenance of VToA systems and processes is extremely burdensome and expensive. For example, numerous private and public phone numbers, which change frequently, have to be updated and maintained in various systems and gateways. As moves, adds, changes, and deletions occur, each VToA gateway must be updated with the relevant changes. This is a critical task that is onerous and expensive to perform and fraught with potential errors.
In a traditional telecommunications or voice network, signaling can be in-band or out-of-band. Signaling may be used to setup and establish voice circuits, to provide Intelligent Network (“IN”) or Advanced Intelligent Network (“AIN”) services and features, and to disconnect voice circuits. In an ATM network, where an SVC is established to support VToA, signaling is achieved through the use of ATM messages, such as those used to setup and disconnect SVCs. Unfortunately, such ATM signaling does not support IN or AIN to provide the advanced telephony services and features commonly found in traditional voice telecommunications networks. This significantly reduces the attractiveness of VToA as compared to traditional voice telecommunications networks or even some other data or packet networks capable of providing voice or telephony communications services.
More particularly, a serious problem and drawback of existing VToA systems and methods is the difficulty or inability to institute advanced calling features or policies on an ATM network-wide basis. Unfortunately, many customary and advanced voice telephony services, which are often available through traditional telecommunications networks designed to transport and support voice telephony, such as circuit-dedicated telecommunications networks, are not available or easily achieved or implemented with VToA. For example, the capability to easily and efficiently provide closed user groups is not available with VToA.
The closed user group service is a valuable service or feature of modern telecommunications systems, especially those used in business enterprises. Telecommunications specifications exist that provide the closed user group service. Unfortunately, these specifications rely on the availability of an interlock code, which is not defined in ATM.
An interlock code provides a mechanism in which only one of the closed user groups is designated for each call. Thus, under such a mechanism, closed user group policies can be enforced on each call using the one closed user group designated for the call. Although a user may be a member of numerous closed user groups, at any given moment, a user can only operate under one of the numerous closed user groups in which it is a member. Unfortunately, the capability to provide interlock code functionality does not exist in ATM. This greatly hampers any potential implementation of closed user groups in ATM.
Generally, closed user groups allow various users to be grouped so that calling privileges may be applied to groups. For example, various user groups of an enterprise might be defined to include the engineering, finance, and marketing groups of a business enterprise. Various combinations of these user groups may be combined to form a closed user group. Each such user group of a closed user group may have certain privileges established to control such things as the capability to originate a call to another user of the same closed user group, the capability to receive a call from another user of the same closed user group, the capability to originate a call to another outside of the closed user group, and the capability to receive a call from another outside of the closed user group. Unfortunately to implement such a service or feature in a traditional VToA would require that blocking information be provided in various systems and gateways and these would have to be frequently updated. This is impractical, inefficient, cumbersome and expensive to carry out. As is illustrated, this type of a service is problematic to implement in traditional VTOA networks and systems.